Pronunciation: (pen"i-trā'shun),[key] —n. 1. the act or power of penetrating.
2. mental acuteness, discernment, or insight: a scholar of rare penetration. 3. the obtaining of a share of a market for some commodity or service.
4. the extension, usually peaceful, of the influence of one nation or culture into the affairs of another.
5. a military attack that penetrates into enemy territory.
6. Gunnery.the depth to which a projectile goes into the target.
7. the measure of relative depth of field of a telescope or microscope, esp. a binocular microscope.